Develop Reference

Basic Android OS on low end smart watch to transfer information using Bluetooth

Is there a way to purchase a low end smart watch, replace the os with android (not Wear OS) and develop a custom app for it? It is a single purpose device, so I don't need any of the extras that come with Wear OS, but I need much longer battery life and ability to pair w/multiple phones (not simultaneous connection, but quick switching). I need to pair the phone using bluetooth, connect to it from an app (either Android or iOS), send an image/text, initiate a vibration, and send back an ack, with info. Ideally send heart rate as well.
I'm really not sure how to get started. I know how to develop apps in android studio and Wear OS as well, but it's taking me a long time to figure this out and I was hoping somebody might have done it before.
This seemed promising, but it wasn't the exact use case. It would even be great to test on some non smart watch android device or board.

How to make several mobile devices (both iOS and Android) communicate without using internet

I am currently trying to develop a mobile application for both iOS and Android. It basically will be a game buzzer app, determining which of the players is granted a right to answer a specific questions.
The problem is that I struggle to determine which technology / framework I should use for that. Now, some details:
In this app there will be a "base" - it is the phone that gives
"start" signal for all the other players. Each buzzer pressed before this signal corresponds to a false start. Eventually, information
about which player is granted a right to answer or is penalized due
to false start should be displayed on the base device.
App is done for people who have no access to the internet. All the
communication should exists given ONLY mobile phones with no data
plan.
Max number of communicating devices is 9 (1 base and 8 players)
I investigated a lot of resources and this is what I discovered:
Regular WLAN with TCP sockets and etc won't help, since it assumes that all devices are connected to same wireless access point - it violates my requirements.
Regular bluetooth won't help either. This would work across a specific platform, but making Android talk to iOS is impossible.
Situation with Wi-Fi direct is same as with regular bluetooth. Both platforms support this, but Apple's MultipeerConnectivity framework works only with iOS devices.
Now the last option I am left with is BLE. Both platforms support this and are able to intercommunicate (acting both as central or peripheral devices). However, due to my requirements for an app, I assume that base device should act as peripheral, and according to (sometimes conflicting) articles on Internet, one can't connect several central devices to single peripheral.
Now, my questions:
I still assume I might have done some mistakes in the bullet points above, so please, correct me if I am somewhere wrong.
Now when I am left only with BLE option, are there any possible solutions to the above issue? Maybe it is possible to use all devices as centrals (?). I recently saw this example, where everything works cool. Sorry in advance, if I said something stupid.
Of course, there is a counterexample - FireChat, which employs OpenGarden's MeshKit. But the framework is not available. I tried communicating OpenGarden people, but no response. Does anyone know if it is planned to go opensource soon, or maybe there exists any analog of this?

Try the Hype SDK by Hype Labs. It's a multi-transport, multi-hop mesh SDK. It supports interoperable Bluetooth Low Energy (and other transports as well). The SDK is currently in private beta but will be made available upon approval of the subscription.

AntiVirus kills my application

I am working on an Android application that uses Bluetooth to communicate with a nearby PC.
The app works greatly on my own device (Samsung Galaxy Note 3 - CM 12.1) but on of my beta-testers it does not.
Simply put the app allows people to write and receive SMS from their
PC (with my C# WPF app) via Bluetooth & their phone.
My beta-tester is using a Samsung Galaxy Note 4 stock ROM (Lollipop).
At first I thought when his screens turned off, Android would kill the MainActivity which holds on a few threads including the one maintaining the connection alive (with a inpustream.read() blocking method). Such behavior does not occur on my own device : I could keep the connection alive for a whole night without plugging my phone.
I was warned, though, that using services would avoid such problem because Android does not behave the same way from one device to another. So I updated my app and made my MainActivity use my MainService to spawn the relative threads. But it did not change a thing.
As my title suggests, the problem lies with his antivirus and more precisely : AVG.
I have no knowledge on how such antivirus work on Android and I don't even use one. By freezing AVG with Titanium Backup on his rooted Galaxy Note 4, my app stopepd crashing and is now working perfectly well as intended.
So I wonder, how come AVG deciced to kill my app when the device screen turned off?
How should my app behave so that this won't happen with any other users using AVG or any other antivirus ? What should I do so that my app does not look as a suspect ?

I don't know exactly what the AVG did to your app.But I think that AVG may don't let your app force to turn on the bluetooth or use the Bluetooth when Android device is sleep or send/receive SMS.The AVG is one kind of antivirus apps that most of them have lots of permission request limited or power saving strategy,especially on rooted Android devices or the first part app already in the Android ROMs.
Try to make clear that what's the real point AVG did to your app.And then try to solve your problems with gentle and smart.
For example：
1.If the AVG doesn't let you use BluetoothAdapter.enable() to force to turn on the Bluetooth, try to use Activity.startActivityForResult() to let users to choose whether turn on Bleutooth or not.
2.If the AVG doesn't let you use Bluetooth when the Android device is sleep.You can try to use WakeLock.acquire() to hold the Android device.
3.If the AVG doesn't let you use SMS sending or receiving.You can changed another communication protocol, SPP or BLE or something else.
Maybe you have heard Xiaomi.If you are an Android Developer in China,because Xiaomi is very popular in China,you must deal with the adaption with Xiaomi,and then you will find that Xiaomi is really fucking for Android Developers in China.
Xiaomi doesn't some really amazing things to the original Android.For example:
1.
AlertDialog..getWindow().setType(WindowManager.LayoutParams.TYPE_SYSTEM_ALERT);
you can't alert the TYPE_SYSTEM_ALERT dialog on some xiaomi ROMs that they tell you nothing.
2.Xiaomi has modified lots of original themes.
3.Xiaomi has changed the Android alarm timing mechanism while the device is sleep which is called Wake-Up-Alignment.This is really terrible for the apps that with the function of timing.
The above problems are that I met in Android development, some problems I can resolve it, some you don't have any chances to change it.
Remember that:The adaption with Android devices is that you must make your users know you app works on most of the popular Android Devices,the developers try to make the app run on most Android devices,but it maybe not work on some Android devivces with customized ROMs or with some special third part apps.That's it ,that's true, that's Android.
If the problem can't be solved,it's not a problem!

Rhomobile, BLE112 Bluetooth device - iOS and android app

I have been searching for a while now and decided to post a question here to see if someone had already traveled down this specific road.
I am developing a bluetooth enabled device, using the Bluegiga BLE112 chip. They announce this chip to be easily used with iOS devices (and this was our main reason for choosing it)
The device will need to communicate with an App, that we need to be developed for iOS, Android, Windows Phone, and Blackberry. Due to this need, I've decided to use Rhomobile, as it seems to be the only one that supports developing BT apps for iOS without having to develop further plugins.
I only need to send small messages (like commands, small strings) and sometimes a bigger file to the device's internal memory.
On Rhomobile's BT documentation, they state that for iOS it is only possible to comunicate between iOS devices ( i'm thinking that they say this because of the MiFi limitations imposed by Apple, but that using Bluegigas chip are not a problem...)
My question is:
Since Bluegiga's documentation has examples of devices communicating with iOS using their chip, i should be able to develop using Rhomobile and not suffer from the limitation stated above. I wanted to be as sure as possible before making my company spend money ordering the chips and development board and what not..
Has anyone tried this, is my thinking missing something?
Thank you all for your time.
Daniel

Good Question, I think I can understand the reason for your confusion.
The main reason is many people/products/frameworks does not clearly mention if they are talking about Bluetooth Classic or Bluetooth Low Energy (BLE).
These are both 2 different things and even thougfh they are called "Bluetooth" one cannot talk to the other.
(Some devices can be both Classic and Bluetooth Low Energy, which allows it to connect to either types)
Ok now comming to your Question :
THE bluegiga dongle is BLE
The Rhomobile is refering to the Bluetooth Classic version of the API.
On iOS the BLE APIs are open to applications, but Classic is limited on iOS , one way for Apps to use Classic Bluetooth on iOS is via the Gamekit APIs but that is possible only when talking with iOS devices, so it wont connect to another Android or Win device that is also Classic.
Needless to say with BLE APIs you cannot connect to calssic anyways.
The bluegiga examples are BLE examples, and apple also has good documentation and examples / samples on how to use BLE so yes it is easy to build a device and app using BLE on iOS.
There is nothing special abut any particular chip yo ucan use any BLE chip - there are many vendors today.
BUT Android (and I guess Windows as well) does not yet have BLE APIs for applications to use :( (Bit I think is is comming soon :))
So I hope this clears things up a bit.

Analog video capture to Android phone

I am looking for a way of displaying an analog video stream on an android phone. On a pc/mac/etc you can achieve this using a cheap usb analog-digital converter such as a grabby: http://www.terratec.net/en/products/Grabby_82248.html, and then view on VLC, for example.
Would such a thing work (in theory) on android if the proper drivers were available? (ie. are there any hardware issues which make this impossible?)
Does anyone know if such a device with android drivers is available?
Ultimately I want to make an app which interfaces with the grabby (or similar device) and allows the user to view video on the android and capture and send short clips.

First of all the Android device needs to support USB Host. This limits your userbase significantly.
Then there is the problem with power. Some USB Host devices will be incompatible simply because an Android phone will not be able to push enough power through to port to get it running properly.
I'm not sure about the drivers, but I'm 99% sure it won't work "out of the box".
You should certainly take a look at THIS project. It is pretty similar to what you are trying to do. Maybe you should consider getting in touch with that person.
EDIT:
Based on what it took to get that DVB-T dongle running in the project i mentioned above the chances of creating an app that everyone will be able to simply download and use are EXTREMELY slim. Getting that dongle running required using a modified kernel and special scripts. Of course I could be wrong. You can continue the research yourself or wait for someone with more experience than me to reply.